Burners for vaporised liquid fuels



Oct, 7, 1958 I G. \N. F. RICHARDS 5,

BURNERS FOR VAPORISED LIQUID FUELS Filed Sept. 19, 1955 14 770R/VE);

United States Patent BURNERS FOR VAPORISED LIQUID FUELS George WilliamFrancis Richards, London, England, as-

signor to Lion Stamping Company Limited, London, England ApplicationSeptember 19, 1955, Serial No. 535,207

Claims priority, application Great Britain September 24, 1954 4 Claims.(Cl. 158-89) This invention relates to burners for vaporised liquidfuels.

The type of burner with which the invention is concerned is that inwhich the combustion chamber is defined by two perforated shellsarranged coaxially one within the other and within a shroud which, withthe outer shell, defines a space through which combustion air passes tothe combustion chamber through the perforations in that shell.

The type of burner can be made to give good service both as to its heatoutput and its efficiency. It'is, however, found to suffer from thedisadvantage of being sensitive to draughts. If, for example, a spaceheater embodying such a burner is placed near a door, the draught causedby opening the door is liable to upset the even flow of vapour throughthe combustion chamber and to result in popping noises which persist fora time which depends on the violence of the draught and on the generaldesign of the burner.

The object of the invention is to make a burner of the type in questionless sensitive to draughts.

That object is achieved by restricting the air inlet while, of course,providing an adequate supply of air and forming the inlet so that a gustof air from the outside does not tend to pass directly through theperforations in the outer shell into the combustion chamber.

In the burner in accordance with the invention, the space defined by theshroud and the outer perforated shell is in communication with thecombustion space above the top of the outer shell and is closed at thebottom, the supply of air to the space being effected through holes ator near the lower end of the space, which holes are formed or providedwith baflles so as to direct the incoming air away from the outerperforated shell.

In the preferred form of the invention, the holes are formed in a platewhich closes the lower end of the space between the outer perforatedshell and the shroud. In this form, best results have been obtained bythe use of holes formed by making slits in the closing plate parallel tothe periphery of the shroud and pressing down the material of the platewhich lies on the shroud side of each slit and pressing up the materialwhich lies on the opposite side.

In order that the supply of combustion air may be I adequate the totalarea of the holes must be at least as reference to the accompanyingdrawings in which:

Figure l is an elevation, partly in section of one form of theinvention;

Figure 2 is a perspective view of the closing plate shown in Figure 1 asseen from below the burner;

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Figure 3 is a fragmentary view of a modified form of part of the burnershown in Fig. 1.

The burner shown in Fig. 1 has a combustion chamber 10 defined by twoperforated shells 11 and 12 which are arranged coaxially one within theother. The two perforated shells are located within a shroud 14 whichwith the outer perforated shell 12 defines a space 13 through whichcombustion air passes to the perforations in the shell 12 as will beexplained below.

The space 13 is in communication with the combustion chamber 10 abovethe top of the shell 12, the major part of the combustion taking placein the space 16 and the combustion products passing through outlets 17and 18 in the shroud 14 and an outer shroud 19 respectively to a coil 20and a gauze dome 21 which are thus caused to glow.

The space 13 is closed at the bottom by a closing plate 22 which isprovided with a number of holes 23 forming at the lower end of the space13 an inlet for the supply of the combustion air.

An extra supply of combustion air is led through the space 25 betweenthe two shrouds 14 and 19 to ensure complete combustion of the vapourbefore the combustion products pass to the atmosphere.

The holes 23 in the closing plate 22 are formed by making slits in theplate parallel to the periphery of the shroud 14, pressing the materialof the plate on each side of the slits in opposite directions so as toform .baflies 24 and 26 as shown in Figs. 1 and 2.

In the normal burner, the space 13 between the shroud 14 and the shell12 being open, a sudden increase in the air supply such as is caused bya gust due to a swinging door or the like, is transmitted immediatelyand directly to the combustion chamber through the perforations in theouter shell 12.

In the modified burner, as can be seen from Figs. 1 and 2, the bafiles24 and 26 bounding the air inlet holes 23, direct the incoming air awayfrom the shell 12. This, it is found, stops the disagreable popping towhich the normal burner is prone. While a sudden gust may produce a popor two, the popping does not persist over any appreciable period, normalsteady combustion being very rapidly re-established.

Fig. 3 shows a modification of the closing plate 22 of the burnerdescribed with reference to Figs. 1 and 2.

Here, the lower end of the space 13 is closed by a plate 22 providedwith air inlet holes 62 which are baflled by a ring 64 having aninclined flange 66 which partly overlies the holes and serves to directthe incoming air away from the shell in much the same way as do thebaflles 26 shown in Figs. 1 and 2.

In all the burners described, the air inlet holes must have a total areaadequate to allow sufficient air to be supplied for proper combustion ofthe fuel. Their total area must be at least equal to that of theperforations in the outer shell 12. Because of the bathing effect whichis produced in accordance with the invention, it is, however, founddesirable that the area of air inlet holes be somewhat in excess of thatof the perforations. In practice, it is found that an excess of up toabout 5% is desirable.

It is not essential that the whole of the air supply be bafiled. A minoramount of the air can be supplied through unbafiled holes such as theholes 30 shown in Fig. 2. These holes, as shown, should be near theshroud 14 rather than near the shell 12. They also serve as a convenientmeans whereby the manufacturer can adjust the total area of the airinlet holes as required.

The following is a typical example:

With a shroud 14 of 4% inches diameter and an outer perforated shell 12of 3 inches diameter at the bottom, excellent results have been obtainedwith an arrange- J ment having the proportions shown in Fig. 1, theholes 23 having dimensions X, Y and Z (see Figs. 1 and 2) 0f /2 inch, 7inch and A; inch respectively.

The greatest benefit is obtained from the invention if it is used in aburner having a combustion chamber the cross-sectional area of which, asshown in the drawings, increases progressively upwards, this beingachieved by the use of tapering shells 10 and 12 or the use of onecylindrical and one tapered shell.

What I claim is:

1. A vaporised fuel burner comprising, an inner upwardly flaredperforated shell, an outer upwardly flared perforated shell surroundingsaid inner shell in coaxial relationship therewith to define an annularcombustion chamber, a shroud surrounding said outer perforated shell incoaxial relationship therewith to define an annular combustion airspace, the upper end of said shroud defining with the upper end of saidinner shell a combustion space located above the upper end of said outerperforated shell, at least one wire element arranged above saidcombustion space and in the path of products of combustion passing fromsaid combustion space to atmos phere, the upper end of said combustionair space being in communication with said combustion space and thelower end of said combustion air space being closed by an aperturedplate, the apertures in said plate being provided with baffles wherebyat least the major part of the incoming air is directed away from theperforations in said outer perforated shell.

2. An open-topped vaporised fuel burner having a combustion chamberdefined by inner and outer perforated shells arranged coaxially onewithin the other, and a shroud surrounding the outer shell and definingthere- 4- with a space through which combustion air passes to andthrough the perforations in that shell, said shroud extending above theouter shell and provided with an inwardly directed lip cooperating withthe inner shell to provide an additional space immediately above the topof the outer shell communicating with the first space, and said firstspace being bounded at the bottom by an annular plate having thereinholes for the supply of air to the first space, the said holes beingprovided with baffles arranged so as to direct at least the major partof the incoming air away from the outer perforated shell.

3. A burner according to claim 2 in which the holes are formed by makingslits in said annular plate parallel to the periphery of the shroud andpressing down the material of the plate which lies on the shroud side ofeach slit and pressing up the material which lies on the opposite side.

4. A burner according to claim 3 in which the total area of the holes isgreater than that of the perforations in the outer shell but does notexceed the area of those perforations by more than 5%.

References Cited in the file of this patent UNITED STATES PATENTS1,290,856 White et al. Jan. 7, 1919 1,516,317 Stockstrom Nov. 18, 19241,613,020 Chadwick Jan. 4, 1927 2,546,731 Duff Mar. 27, 1951 FOREIGNPATENTS 148,327 Austria Dec. 28, 1936 152,616 Austria Feb. 25, 1938

